1. Field of the Invention
The present invention relates to lens drive devices installed in image pickup devices. More specifically, the present invention relates to a lens drive device moving a lens in the optical path direction by use of a cam member.
2. Description of the Related Art
Recently, an image pickup apparatus, such as a still camera or a camera built in a mobile phone, has been smaller in size significantly. There is such an image pickup apparatus which includes a lens drive device moving a lens to a focused point in accordance with the position of the object. Thus, the lens drive device which has a smaller size and a high focus accuracy is required.
Japanese Unexamined Utility Model Application Publication No. 5-61713 discloses a lens drive mechanism which moves a lens in the optical axis direction by use of a cam member. In this lens drive mechanism, the lens can be driven with a simple structure having a cam member. Further, this lens drive mechanism has plural switches for detecting a position of the cam member. The lens drive mechanism recognizes the initial position or a partway position by using these switches, thereby adjusting the focus with high accuracy. More specifically, this lens drive mechanism has a mechanical switch for detecting the initial position of the cam, and a photo interrupter (optical switch) for detecting a substantial middle position of the driving range of the cam so as to detect the position of the cam.
The above lens drive mechanism disclosed in Japanese Utility Model Application Publication No. 5-61713 has a simple structure, since the cam structure drives the lens. However, the above lens drive mechanism detects the position of the cam member by using the plural switches. This requires a space for arranging the switches within the mechanism, thus enlarging the structure of the lens drive mechanism. In accordance with this, plural expensive switches are used, thereby causing a problem of increase in the manufacturing cost.